The 2 CSF proteins (MW 26 and 29 k daltons) that were found previously in only Creutzfeldt-Jakob disease and Herpes simplex encephalitis, are absent from other causes of dementia (AIDS-associated dementia, multiinfart dementia, Alzheimer's disease, Huntington's disease, parkinsonism dementia of Guam) and other infections (tuberculous and syphilitic meningitis, and encephalitis from measles, cytomegalovirus, varicella, rubella, and three togaviruses.) Identification of these proteins in patients with dementia shows potential as a diagnostic test for creutzfeldt-Jakob disease. Two proteins (both of 40 kd) that had been found in the spinal fluid of 30% of schizophrenic patients have been found in a small proportion (20%) of schizophrenics in an independent study, and results from two other populations are awaited. One protein (25 kd) previously found in Parkinson's disease and MPTP-induced parkinsonism, has now been observed in a proportion of patients that have pathology common to the dopaminergic nigrostriatal neurones. Methods have been developed to obtain partial amino acid sequences of all 5 aforementioned disease-associated proteins and results are awaited. The basic mechanism for the visualization of protein and nucleic acids by silver staining has been shown to involve the reduction of ionic to metallic silver. Lysine and histidine, and the sulfur containing amino acids are the primary sites in the silver staining reactions. By utilizing sets of operationally constitutive proteins for the normalization of intra-gel stain intensities, quantitative comparisons of protein concentrations have been made in electrophoretograms from complex biological fluids or cellular extracts.